The present invention relates to an organic solvent composition for film transfer and a method for wet transferring therewith, more specifically, to an organic solvent composition for wet transferring of a transfer film having improved weather-resistance suitable for external ornaments and a method for wet transferring therewith, which comprises a step of transferring patterns directly to the concave-convex surfaces of objects made of various materials such as steel, aluminum, plastic, ceramic, rubber or glass.
It has been well known that transfer films are manufactured to give multi-layered forms which comprise: release layer, protective layer, print layer and adhesive layer in order(see: Japanese Patent laid-open Publication No. (Hei) 9-58196); lubricating layer, print layer, masking layer and adhesive layer in order(see: Japanese Patent laid-open Publication No. (Hei) 7-47798); or, resin layer, lubricating layer, protective primer layer and print layer in order(see: Korean Patent Publication No. 96-2721). Since the prior art transfer films generally comprises basic layer, lubricating layer, print layer and adhesive layer, they have revealed inherent disadvantages that the releasing process is very laborious during wet transfer and the transferring process of desired patterns to the concave-convex surface during thermal transfer is very difficult. In addition, the conventional transfer films have inferior physical properties, such as low paint coat adhesion, poor weather-, alkali- and scratch- resistance(low pencil hardness), and uneven thickness of the painted coat.
Korean Patent No. 269772 discloses a transfer film comprising basic layer, print layer and pliable coat layer, which is designed to solve the said problems. However, they do not consider the weather-resistance of transfer film seriously, even though the film for an external ornament is destined to be exposed to harsh weather conditions like sunlight(ultraviolet), rain and wind for a long period time, which naturally limits its practical application.
On the other hand, numerous methods for transferring films having a variety of patterns to various kinds of concave-convex surfaces have been known in the art:
For example, Korean Patent Publication No. 91-2529 teaches a method of forming a glossy pattern on an object by printing a patterned mold on the surface of the object using a paste material by screen printing, heating it over 400xc2x0 C., dipping the molded object into a solution of metal oxide which is reactive with the uncovered area of the surface of the object, and then removing the mold from the object. Also, several related methods are known in the art, such as described in Japanese Patent Publication No.(Sho)52-41682 and (Sho)57-50547. However, these transfer methods are rather limited in their practical application due to the following disadvantages: transferring processes are laborious; the materials for the objects are limited; the color is easily faded or deteriorated; the patterns should be formed on the object prior to transferring; and, high cost is required to carry out the methods.
In an effort to overcome many limitations of the prior art described above, wet transfer and thermal transfer methods have been proposed in the art.
Thermal transfer method, in general, comprises the steps of pressing the film onto an object using a heated press and then peeling off the resinous support layer, in which films prepared by coating the resinous support layer with the mixture of lubricating resin and organic solvents such as celluloseacetate, methylethylketone (MEK), ethanol or toluene, coating with nitrocellulose and the like thereon to prevent fissure between the said resin layer and print layer while improving adhesive property, and then thereon printing the mixture of urethane resin, dye, and organic solvent such as toluene or methylethylketone. This method is, however, proven to be less satisfactory in the senses that: pressing and removing resinous support layer are laborious, transferring of the films to the concave-convex surface is complicate, and mass production of patterned objects is relatively difficult.
On the other hand, wet transfer method, when applied to the concave-convex surface, is generally accomplished by floating a pattern-transferred film on water, in which the transfer film is prepared by transferring paint or transfer ink to a sheet, transferring the transfer film to the concave-convex surface of an object by means of liquid pressure attained by pressing the object onto the above film, and then dipping the pattern-transferred concave-convex surface into water at 20 to 35xc2x0 C. for 5 to 10 minutes to get rid of paint components in the transfer film, followed by washing with clean water at room temperature and drying in an oven maintained at 100 to 250xc2x0 C., and then repeated coating to get better quality of surfaces.
The wet transfer method essentially employs a step of coating the film with organic solvent before transferring to the object, where direct spraying of organic solvent onto the film floated on water tank is generally carried out. However, the step of applying the film with organic solvent by spraying of volatile organic solvent has revealed disadvantages of the large consumption of organic solvent, as well as the requirement of facilities for environmental protection to prevent the exhaust of organic solvent.
Under the circumstances, there are strong reasons for exploring and developing an alternative method for wet transferring to solve the said problems in the art.
The present inventors have made an effort to develop an improved method for wet transferring of a transfer film with many desirable physical properties where a pulp layer consisting of water, polyvinylalcohol, starch and pulp as main components, and sugar, soap, glue, latex, silicon oil and water-soluble antistatic agent as minor components is laminated with a main film layer consisting of all components of the pulp layer except pulp, on which a print layer is laminated with an ink containing ceramic pigment and fluorinated resin for transfer of various patterns to all kinds of concave-convex surfaces and external ornaments. For wet transferring of the transfer film, an organic solvent composition comprising methylethylketone, xylene, ethyleneglycol monobutylether and isophorone or methylsalicylate is employed, with which the surface of an object is directly coated without spray-coating, assuring uniform coating over the surface of the object to give many desirable physical properties of the pattern-transferred object in terms of coat adhesion, pencil hardness, quality of coating, endurance, acid-, alkali- and weather-resistance.
A primary object of the present invention is, therefore, to provide an organic solvent composition which can be directly applied to the surface of an object during wet transfer of a transfer film.
The other object of the invention is to provide a method for wet transferring using the organic solvent composition.